Lee, Su A.,  L. Vanessa Lagos, Mike R. Bedford, and Hans H. Stein. 2020. Increasing calcium from deficient to adequate concentration in diets for gestating sows decreases digestibility of phosphorus and reduces serum concentration of a bone resorption biomarker. Journal of Animal Science, 2020,  Vol. 98: No. 3:1-8.

Lopez, D. A., L. V. Lagos, and H. H. Stein. 2019. Digestible and metabolizable energy by pigs in soybean meal sourced from different countries. Book of Abstracts. In: 1^st International Feed Technology Congress, Cologne, Germany. p. 26. (Abstr.). Link to Abstract.

Lagos Vanessa, Carrie L. Walk, Hans H. Stein. 2019. Influence of the level of dietary digestible Ca on growth performance, bone ash, plasma Ca, and abundance of genes involved in Ca absorption in 11- to 25-kg pigs fed different levels of digestible P. Journal of Animal Science, Volume 97, Issue Supplement_2, July 2019, Pages 98–99. (Abstr.). Link to abstract

Digestibility experiments have been conducted to determine the nutritional value of an enhanced torula yeast derived from forestry by-products. Results of these experiments indicated that enhanced torula yeast has a greater digestibility of amino acids and P than fish meal, and a concentration of metabolizable energy that is not different from that in fish meal. Therefore, it is believed that the enhanced torula yeast can be included in diets for weanling pigs at the expense of fish meal and other animal protein sources. Therefore, the objective of this experiment was to determine the effects on growth performance, fecal score, and blood characteristics of including the enhanced torula yeast at the expense of fish meal and plasma protein in diets fed to weanling pigs.

An enhanced torula yeast was recently developed as a natural alternative protein source to fish meal and other animal proteins. This ingredient has a lower carbon footprint than other available yeast proteins because it is derived from forestry by-products. The enhanced torula yeast has an improved amino acid (AA) profile, a greater digestibility of AA than fish meal, and an energy value that is not different from that in fish meal. However, there are no data available about the digestibility values of P in this new ingredient. Therefore, an experiment was conducted to test the hypothesis that the values for apparent total tract digestibility (ATTD) and standardized total tract digestibility (STTD) of P in enhanced torula yeast are not different from those in fish meal.

Lee, Su A, L. Vanessa Lagos, Carrie L. Walk, and Hans H. Stein. 2019. Basal endogenous loss, standardized total tract digestibility of calcium in calcium carbonate, and retention of calcium in gestating sows change during gestation, but microbial phytase reduces basal endogenous loss of calcium. J. Anim. Sci. 2019.97:1712–1721. Link to full text.

Lee, S. A., L. V. Lagos, and H. H. Stein. 2019. Digestible calcium and digestible phosphorus in swine diets. In Proc. London Swine Conference, London, ON, Canada. March 26-27, 2019. Pages 63-72. Link full text(.pdf)

Mesina Von G. R., L. Vanessa Lagos, Rommel C. Sulabo, Carrie L. Walk, and Hans H. Stein. 2019. Effects of microbial phytase on mucin synthesis, gastric protein hydrolysis, and degradation of phytate along the gastrointestinal tract of growing pigs. J. Anim. Sci. 2019.97:756–767. Link to full text.

Requirements for P for growing pigs are expressed as the requirement for standardized total tract digestible (STTD) P, whereas requirements for Ca are usually expressed as requirements for total Ca. It is, however, recognized that diets for pigs are most accurately formulated based on a STTD Ca:STTD P ratio, and recent work has generated values for STTD of Ca in most Ca containing feed ingredients, which makes it possible to formulate diets based on STTD Ca.

Recent data from the University of Illinois have indicated that if STTD P is at the requirement, a ratio between STTD Ca and STTD P that is less than 1.35:1, 1.25:1, and 1.10:1 maximizes growth performance of pigs from 25 to 50 kg, 50 to 85 kg, and 100 to 130 kg, respectively. However, the STTD Ca:STTD P ratio needed to maximize bone ash is greater than the ratio needed to maximize growth performance. An attempt to estimate the requirement for STTD Ca by pigs from 11 to 25 kg was also made, but due to a reduction in ADG and G:F as dietary Ca increased, an optimal STTD Ca:STTD P ratio could not be estimated.

Calcium may be absorbed by transcellular or paracellular transport. Transcellular transport is the primary route if dietary Ca is low, but if dietary Ca is adequate or high, Ca is mainly absorbed using the paracellular route via the tight junctions. However, there are limited data demonstrating effects of dietary Ca concentration on abundance of genes related to transcellular and paracellular transport of Ca in the small intestine of pigs.

Therefore, the objectives of this experiment were to test the hypotheses that a STTD Ca:STTD P ratio less than 1.40:1 maximizes growth performance of pigs from 11 to 25 kg and that increasing dietary Ca downregulates abundance of genes related to transcellular absorption of Ca and tight junction proteins in the small intestine.